The present invention generally relates to an alkaline galvanic cell and more particularly, to an improvement of a sealing portion in a flat-type alkaline galvanic cell, in which a layer of epoxy adduct polyamide amine having amine valence in the range of 50 to 400, and another layer of chlorosulfonated polyethylene are provided between an innermost copper layer of an anode sealing plate and an insulating packing of the cell for improving leakage prevention.
Generally, as illustrated in FIG. 1, an alkaline galvanic cell of a flat type includes a metallic container 3 serving as a cathode terminal member (referred to as a cathode container hereinbelow) in which a cathode active substance A, a separator S, an electrolyte impregnated material E, etc. are accommodated, and a sealing plate or sealing container 1 serving as an anode terminal member (referred to as an anode sealing plate hereinbelow) in which an anode active substance C is housed. The anode sealing plate 1 is fitted into the cathode container 3, through an electrically insulating packing 2 made, for example, of synthetic resin and closely fitted around the peripheral edge of said sealing plate 1, while a layer of a sealing agent 4 is further provided between the peripheral edge of the sealing plate 1 and the insulating packing 2, with the upper peripheral edge of the cathode container 3 being crimped inwardly as shown for preventing leakage of electrolyte.
For the sealing agent as described above, there have conventionally been proposed various materials, for example, fatty polyamide as disclosed in U.S. Pat. No. 3,922,178, cured product of epoxy resin and polyamide as disclosed in U.S. Pat. No. 3,713,896, asphalt, pitch, micro-crystalline wax, fluoro plastics, etc., with certain effects being available therefrom. However, it is the present situation that a result fully satisfactory can not be obtained, even if such sealing agents as described are employed for the alkaline galvanic cells. Meanwhile, part of the present inventors have come to discover that epoxy adduct polyamide amine is suitable for a sealing agent of the alkaline galvanic cells of this kind.
Therefore, the present inventors have been carrying out research and investigation into a method for further improving the superior effects of epoxy adduct polyamide amine referred to above.